What should I do when my Synology volume has crashed?

A crashed volume means the pool lost more drives than its redundancy could tolerate, so DSM can no longer guarantee the data. This is stressful, but the wrong first move can turn recoverable data into lost data. Slow down.

Do this first

1. Stop writing to the NAS. Every write reduces recovery chances. Stop apps and file access that touch the crashed volume.
2. Do not reinitialize, reformat, or recreate the pool, and do not blindly "repair" or remove drives: these can overwrite recoverable data.
3. Check the drive status in Storage Manager: see which drives are flagged failed and how many. That tells you whether recovery is plausible.

Then choose a path

• You have a backup: the clean route. Verify the backup, then rebuild the pool with healthy CMR drives and restore.
• No backup, data is critical: consider professional data recovery before doing anything destructive. Powering down and consulting a recovery service can preserve options.
• No backup, data is non-critical: you may rebuild the pool and start fresh, accepting the loss.

Why this happened

A crash usually means a second drive failed while the array was already degraded (or during a rebuild). It is the argument for RAID 6 / SHR-2 on large arrays and for keeping current backups. Follow Synology's official crashed-pool guidance for your DSM version, and replace failed drives with CMR NAS drives; the table lists options.